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Teilenummer | TD1482 |
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Beschreibung | 1.6A 23V Synchronous Rectified Step-Down Converte | |
Hersteller | Techcode | |
Logo | ![]() |
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Gesamt 14 Seiten ![]() T echcode®
DATASHEET
1.6A 23V Synchronous Rectified Step-Down Converte TD1482
General Description
Features
The TD1482 is a monolithic synchronous buck • 1.6A Output Current
regulator. The device integrates two 130mΩ • Wide 4.75V to 23V Operating Input Range
MOSFETs, and provides 1.6A of continuous load • Integrated 130mΩ Power MOSFET Switches
current over a wide input voltage of 4.75V to 23V. • Output Adjustable from 0.923V to 20V
Current mode control provides fast transient • Up to 93% Efficiency
response and cycle-by-cycle current limit.
• Programmable Soft-Start
An adjustable soft-start prevents inrush current at
turn-on, and in shutdown mode the supply current
•
Stable with Low ESR Ceramic Output Capacitors
drops to 1µA.
• Fixed 340KHz Frequency
This device, availablein an SOP8
package, • Cycle-by-Cycle Over Current Protection
provides a very compact solution with minimal external • Input Under Voltage Lockout
components.
Applications
• Distributed Power Systems
• Networking Systems
• FPGA, DSP, ASIC Power Supplies
• Green Electronics/ Appliances
• Notebook Computers
Package Types
Figure 1. Package Types of TD1482
October, 20, 2010. Techcode Semiconductor Limited www.techcodesemi.com
1
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DATASHEET
1.6A 23V Synchronous Rectified Step-Down Converte TD1482
Electrical Characteristics(Cont.)
VIN = 12V, Ta = 25℃ unless otherwise specified.
Parameters
Input Under Voltage Lockout
Threshold
Input Under Voltage Lockout
Threshold Hysteresis
Soft-Start Current
Soft-Start Period
Thermal Shutdown *
Symbol
Test Condition
VIN Rising
VSS = 0V
CSS = 0.1µF
Min. Typ. Max.
3.80 4.10 4.40
210
Unit
V
mV
6 µA
1 ms
5
160 °C
Typical Performance Characteristics
Figure 4. Steady State Test
Figure 5. Startup through Enable
October, 20, 2010. Techcode Semiconductor Limited www.techcodesemi.com
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DATASHEET
1.6A 23V Synchronous Rectified Step-Down Converte TD1482
The system has one zero of importance, due to the
compensation capacitor (C3) and the compensation
resistor (R3). This zero is located at:
The system may have another zero of importance, if
the output capacitor has a large capacitance and/or a
high ESR value. The zero,due to the ESR and
capacitance of the output capacitor, is located at:
Determine the C3 value by the following equation:
Where R3 is the compensation resistor.
3. Determine if the second compensation capacitor
(C6) is required. It is required if the ESR zero of the
output capacitor is located at less than half of the
switching frequency, or the following relationship is
valid:
In this case (as shown in Figure 14), a third pole set by
the compensation capacitor (C6) and the
compensation resistor (R3) is used to compensate the
effect of the ESR zero on the loop gain. This pole is
located at:
The goal of compensation design is to shape the
converter transfer function to get a desired loop gain.
The system crossover frequency where the feedback
loop has the unity gain is important. Lower crossover
frequencies result in slower line and load transient
responses,while higher crossover frequencies could
cause system instability. A good rule of thumb is to set
the crossover frequency below one-tenth of the
switching frequency.
To optimize the compensation components, the
following procedure can be used.
1. Choose the compensation resistor (R3) to set the
desired crossover frequency.
Determine the R3 value by the following equation:
Where fC is the desired crossover frequency which is
typically below one tenth of the switching frequency.
2. Choose the compensation capacitor (C3) to achieve
the desired phase margin. For applications with typical
inductor values, setting the compensation zero, fZ1,
below one-forth of the crossover frequency provides
sufficient phase margin.
If this is the case, then add the second compensation
capacitor (C6) to set the pole fP3 at the location of the
ESR zero. Determine the C6 value by the equation:
External Bootstrap Diode
An external bootstrap diode may enhance the
efficiency of the regulator, the applicable
conditions of external BST diode are:
z VOUT=5V or 3.3V; and
z Duty cycle is high:
In these cases, an external BST diode is
recommended from the output of the voltage regulator
to BST pin, as shown in Fig.14
Figure14.Add Optional External Bootstrap Diode to Enhance
Efficiency
The recommended external BST diode is IN4148, and
the BST cap is 0.1~1μF.
October, 20, 2010. Techcode Semiconductor Limited www.techcodesemi.com
12
12 Page | ||
Seiten | Gesamt 14 Seiten | |
PDF Download | [ TD1482 Schematic.PDF ] |
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